The effect of fresh and frozen embryo transfer on maternal and perinatal results in pregnancy by assisted reproductive therapy

INTRODUCTION AND AIM: We planned to show the effect of different embryo transfer (ET) methods on maternal and perinatal outcomes in IVF pregnancies after fresh embryo transfer (TET) and frozen embryo transfer (FET). MATERIAL AND METHODS: The files of 1506 patients who underwent ET at Sakarya Eğitim ve Araştırma Hastanesi Center for Assisted Reproductive Techniques between April 2017 and March 2022 were scanned. 136 of 147 patients who gave live birth were included in the study and two groups were formed according to TET and FET. For endometrial preparation in FET cycles, estrogen and then hormonal method (HY) in which progesterone is added to estrogen was used. The data of the women in both groups during the 6-month postpartum follow-up after pregnancy and delivery were recorded. The groups were compared in terms of maternal, fetal and perinatal outcomes of newborn babies. RESULTS: The groups were similar in terms of age, body mass index, causes of infertility and comorbidities. TET was performed in 45,3% of the patients and FET was performed in 54,7% of the patients. Biochemical pregnancy positivity was 19,21% vs. 17,71%, and live birth rates were similar as 10,41% vs. 9,22% (p= 0,457; p= 0,721). Multiple pregnancy rates were similar in both groups. While there was no difference between the TET and FET groups in terms of days of gestation, preterm birth, birth weight, and baby gender, the rate of babies with a large for gestational age (LGA) was higher in the FET group (p=0,038). Pregnancy induced hypertension (PIH) were relatively higher in the FET group (p= 0,097). The rate of hospitalization in the neonatal intensive care unit (NICU) was higher in babies born after FET (p=0,022). CONCLUSION: It was determined that the risks of PIH, LGA fetus and hospitalization to the NICU may be higher in pregnancies following FET after endometrial preparation with HY in IVF treatment, compared to TET pregnancies. Prospective, randomized, controlled research results are needed to compare the data of large-series case groups in women who underwent TET, FET after HY, and FET in the natural cycle in order to make a healthier assessment on the subject. Keywords: Fresh embryo transfer, frozen embryo transfer, in-vitro fertilization, maternal outcomes, perinatal outcomes.